This project will investigate the impact of setting variables (physical and social environments in which a drug is used) on the long-term, regular, and moderate, i.e., "controlled" use of heroin and other opiates. At least 40 controlled users, including some already followed through a pilot project, will be studied for 2 years. A small number of compulsive opiate users will also be interviewed to provide comparative data. Longitudinal data on controlled subjects will be gathered by the research team and indigenous data gatherers by means of initial and follow-up depth interviews and limited observation. Data will be validated through interviews with 2 friends for each controlled subject. Analysis will include the influence of drug variables (pharmacological characteristics of opiates) and set variables (users' personality). Primary emphasis will be on determining how social sanctions (customs and beliefs surrounding non-medical drug use), and other setting variables operate to promote controlled use and prevent compulsive use or addiction. This project will generate testable hypotheses concerning how setting variables might be manipulated to assist addicts in achieving controlled use, and how other new prevention and treatment strategies might be developed based on a model of controlled use.